Lost Gustav Klimt painting sold at auction

A painting by Austrian artist Gustav Klimt, thought lost for 100 years, will be sold at auction in Vienna.

There are many unanswered questions about the unfinished painting, “Portrait of Fraulein Leiser,” which Klimt began in 1917—a year before his death.

There is also controversy about who the woman in the picture is, and what happened to the painting during the Nazi era.

The painting is estimated to be worth up to €50 million ($53 million; £42 million), although it could fetch a higher price.

It is believed to depict one of the daughters of Adolf or Justus Leiser, who were brothers from a wealthy family of Jewish industrialists.

Art historians Thomas Nutter and Alfred Weidinger say that the painting belongs to Margaret Constance Leyser, the daughter of Adolphe Leyser.

But the M. Kinski auction house in Vienna, which is auctioning the artwork, notes that the painting could also depict one of Justus Leiser's daughters and his wife Henriette.

Henriette, known as Lily, was a patron of modern art. She was deported by the Nazis and died in the Auschwitz concentration camp during the Holocaust.

Her daughters, Helen and Annie, survived World War II.

The exact fate of the painting after 1925 is “unclear,” the auction house said in a statement.

“What is known is that the consignor’s legal predecessor acquired it in the 1960s and it passed to the current owner through three successive inheritances.”

The identity of the current Austrian owners has not been announced.

The painting is being sold on behalf of these owners and the legal successors of Adolf and Henriette Leyser, based on the Washington Principles – namely International agreement To return works of art looted by the Nazis to the descendants of the people from whom the pieces were taken.

“We have an agreement, according to Washington principles, with the whole family,” Ernest Bloel of M Kinski told the BBC.

The M. Kinski catalog described this agreement as a “just and equitable solution.”

But Erika Jacobovits, executive director of the Presidency of the Austrian Jewish Community, said there were still “many unanswered questions.”

She called for an “independent party” to investigate the case.

“The restoration of works of art is a very sensitive issue, and all research must be carried out meticulously and in detail, and the result must be understandable and transparent,” Jacobovits said.

“We must ensure that there is also a developed procedure for special compensation in the future.”

Klimt's artworks have fetched huge sums at auction in the past.